[Damo]

I'm doing a little troubleshooting and decided to finally hook up my check engine light, but i'm not sure if I have it correct because the light isn't doing anything.

I connected one terminal of a 12v globe to what I believe is the correct wire, It is purple with a yellow trace. The other side of the globe was connected to a 12v source that comes on with the ignition.

I turn on the ignition and bridge the 2 wires on the diag plug it does nothing. What am I doing wrong?

[royce]

does the light come on when you turn the ignition on then off once the engine is running?

[Damo]

royce wrote:

does the light come on when you turn the ignition on then off once the engine is running?

Nup, doesn't come on at all. If there is nothing wrong will the light come on? It just occurred to me that all might actually be well. I might try to disconnect a sensor and see what happens.

[royce]

yeah it will when you start it up, jsut like the alt light more or less

its a self test thing

should the light earth not be powered? check the ecu side with a meter?

[Damo]

royce wrote:

yeah it will when you start it up, jsut like the alt light more or less

its a self test thing

should the light earth not be powered? check the ecu side with a meter?

ah ok then, so the CE light should come on with the ignition.

My understanding is that the CE light is grounded through the ECU. Are you saying that the ECU should be providing a voltage on that pin?

[PJ.zook]

Damo the light should come on with the ignition.
The Violet with yellow trace could be one of the wires for the diagnostic plug. Try the plain Violet (purple) wire.

[Damo]

PJ.zook wrote:

Damo the light should come on with the ignition.
The Violet with yellow trace could be one of the wires for the diagnostic plug. Try the plain Violet (purple) wire.

Hey PJ, yes the purple/yellow wire is one of the ones that goes to the diag plug, but from how I read some doco I have, it is also connected to the CE light. I'll have a look for the purple one.

[bron5on]

I have some photos somewhere of the back of my instrument cluster where i modded it for the vss and check engine light. Will see if I can find em and post em tonight. Might be of some assistance to ya.

[Damo]

bron5on wrote:

I have some photos somewhere of the back of my instrument cluster where i modded it for the vss and check engine light. Will see if I can find em and post em tonight. Might be of some assistance to ya.

Cool, i would b interested to see what you have done.

[bron5on]

Ok, short answer is, one side of the light goes to the check engine wire in the vit loom and the other side goes to ign positive. But because we all love pics:


Here we have my sierra instrument cluster laid out on the kitchen table modded to accept the vss, tacho signal and check engine light for the 1.6 16v. The cluster itself isn't upside down, only the writing on the flexy circuit board. I have a mate who is an auto sparky who can take most of the credit for how we set this up. In this pic the speedo unit from the donor vit has already been installed into the instrument cluster. The brown wire is the tacho signal which is connected to the dark brown tach wire in the vit loom. The yellow wire is the vss signal from the vit speedo to the vit loom/ecu. From memory the vss line into the ecu is also yellow. The other terminal for the vss was earthed to the flexy circuit by scraping the plastic coating away from the circuit. For those not familiar with the sierra cluster, the terminals for the vss already exist in the circuit board, they just aren't utilised. As does the check engine light.


Now this is the bit you're interested in Damo. The green and white wires show how we connected up the check engine light. The green wire is connected to the check engine wire in the vit loom(violet with yellow stripe). The white wire is connected to an ign positive wire in the loom (black with white stripe). At least I think it's an ign positive. I don't have a wiring diagram handy and I did this pretty early in the year. Can someone please verify this? If i'm wrong and it's ground then my short answer at the top of this post is also wrong!
You can see how we have simply soldered the wires to the flexy circuit either side of the check engine light. Then we scraped away the copper from the circuit to seperate the wires essentially making two terminals. My check engine light now comes on when I turn the key to ON and then goes out when the car starts. Hope this helps matey.
I have more pics of the other connections on the cluster if anyone needs to look at the tacho and vss connections. Cheers peoples!

[royce]

Black/White is ignition power

[bron5on]

royce wrote:

Black/White is ignition power

Thanks Royce! Will edit!

[Damo]

Thanks for doing that Bronson, that was how I though it should be. Just to be 100% sure, I found some of my doco and double checked and it's definitly correct.

I think my problem is elsewhere in the loom, i'll do some more digging tonight.

[PJ.zook]

Nice bronson, thats how i did it too.
You will also find many spare pins in the two dash plugs too, you can utilise them so you arent running a third cable from the dash.

[steak_knife]

And if you can find the wire's that go to the Obd1 connector to, it's got me beat why people cut these plug's out

[Damo]

steknig wrote:

And if you can find the wire's that go to the Obd1 connector to, it's got me beat why people cut these plug's out

What does the OBD1 connector look like? I had that whole section of the loom out of the vehicle and the only connector I have is the 6 wire diagnostic connector, which is what I used to bridge out 2 terminals to get the codes.

Speaking of which, I managed to get the CE light working!!! After a lot more searching through the loom checking things I put it all back together and... it still didn't work. I tapped the 12v globe with my finger a couple of times and hey presto it worked

[bron5on]

Damo wrote:

steknig wrote:

And if you can find the wire's that go to the Obd1 connector to, it's got me beat why people cut these plug's out

What does the OBD1 connector look like? I had that whole section of the loom out of the vehicle and the only connector I have is the 6 wire diagnostic connector, which is what I used to bridge out 2 terminals to get the codes.

Speaking of which, I managed to get the CE light working!!! After a lot more searching through the loom checking things I put it all back together and... it still didn't work. I tapped the 12v globe with my finger a couple of times and hey presto it worked

Nothing like a bit of percussive maintenance. Hit things until they work! Is the OBD1 plug the smaller of the 2 diagnostic plugs? I mounted both of mine in the glovebox with the ecu and relays. Kinda full in there now!

[steak_knife]

I will try to find that adapter tomorrow & post a pic of it, will be the female side but you will get the idea.